The present invention relates generally to enclosures for interconnecting at least one optical fiber of a feeder cable with two or more optical fibers of a distribution cable. More particularly, the invention relates to an outdoor cabinet comprising at least one coupler module for splitting an optical signal carried by an optical fiber of a feeder cable into optical signals carried on two or more optical fibers of a distribution cable at a local convergence point in an optical network.
Telecommunications service providers are currently developing networks consisting entirely of fiber optic components to meet the demand for high bandwidth communications service to businesses and homes. These xe2x80x9call-opticalxe2x80x9d telecommunications networks require a series of service enclosures, referred to herein as xe2x80x9ccabinets,xe2x80x9d along the network that are located at access points in the field. Each such location is referred to herein as a xe2x80x9clocal convergence pointxe2x80x9d and each such cabinet is referred to herein as a xe2x80x9clocal convergence cabinet (LCC).xe2x80x9d An LCC is utilized at a local convergence point to interconnect an optical fiber of a feeder cable from a service provider with two or more optical fibers of at least one distribution cable. In some instances, an optical fiber of the feeder cable is connected to two or more optical fibers of drop cables that are routed directly to the businesses or homes of subscribers of the communications service. In other instances, an optical fiber of the feeder cable is connected to two or more optical fibers of a cable that is routed from the LCC to yet another local convergence point along the optical network to serve as a further feeder cable for additional drop cables. The further feeder cable is sometimes referred to in the art as a xe2x80x9cbranchxe2x80x9d cable. The optical network may be configured in many different ways, but typically, is configured with one or more feeder cables from the service provider having optical fibers that are interconnected with optical fibers of a plurality of distribution cables at various local convergence points. The distribution cables serve as drop cables routed directly to communications equipment belonging to subscribers, or as branch cables routed to other local convergence points. As used herein, the term xe2x80x9cdistribution cablexe2x80x9d includes both drop cables and branch cables, as those terms are commonly understood by one skilled in the art. Furthermore, the term xe2x80x9coptical fiberxe2x80x9d or xe2x80x9coptical fibersxe2x80x9d as used herein includes coated and uncoated (i.e., bare) single fibers, jacketed fibers (e.g., tight-buffered and loose buffered), multiple fibers, multiple fiber ribbons, and fiber optic cables containing one or more optical fibers.
While fiber optic networks have traditionally served as the trunk line or xe2x80x9cbackbonexe2x80x9d of telecommunication networks to transmit signals over relatively long distances, all-optical networks are gradually being extended closer to the end points of the network. In this regard, fiber optic networks are being developed that deliver fiber-to-the-home, fiber-to-the-business, fiber-to-the-desk, and the like. In each of these applications, the LCC must be capable of interconnecting optical fibers of a feeder cable with optical fibers of distribution cables to establish the desired optical connections. In existing optical networks, the optical fibers of the feeder cable are oftentimes interconnected with optical fibers of the distribution cables within an enclosure that is mounted on a concrete pad (commonly referred to as xe2x80x9cpad-mountedxe2x80x9d and illustrated in FIG. 1A) or mounted on a telephone pole (commonly referred to as xe2x80x9cpole-mountedxe2x80x9d and illustrated in FIG. 1B). In either case, the enclosure typically includes an outdoor cabinet defining an interior compartment that is attached to a removable base. The outdoor cabinet is adapted to protect the optical fiber connections from adverse environmental effects, and if necessary, unauthorized access. At the same time, the cabinet is designed to optimize the number of connections that can be made within the cabinet. Typically, the physical size of the cabinet increases as the number of connections increases. In existing cabinets, the optical fibers of the feeder cable are interconnected (e.g., spliced) in a one-to-one relationship with the optical fibers of the distribution cables. Thus, the number of optical connections that can be made within the cabinet, commonly referred to in the art as the xe2x80x9cfiber capacityxe2x80x9d of the cabinet, is limited by the number of one-to-one connections (e.g., splices) that can be accomplished within the volume constraints of the cabinet. As the all-optical network proliferates, it is anticipated that the number of optical connections required to be made within a given cabinet will soon exceed the fiber capacity of conventional outdoor cabinets.
It is further anticipated that the demand for high bandwidth communications service will require the number of optical fibers of the feeder cable to increase dramatically as the all-optical network proliferates. Since many feeder cables are already installed in fiber optic cable ducts that are buried underground, and because there is oftentimes a physical or operational limit to the number of optical fibers that can be contained together within a feeder cable, there will soon be too few optical fibers from service providers to meet the increased demand for high bandwidth communications service to businesses and homes. It will therefore be necessary for service providers to install additional feeder cables within existing fiber optic cable ducts, or to invest in the construction of additional fiber optic cable ducts to carry the additional feeder cables. In certain instances, neither solution may be feasible, practical or cost effective. In any event, substantial capital expense will have to be incurred by the service provider. The capital expense incurred by the service provider ultimately will be passed on to the subscriber in the form of higher cost communications service.
As the all-optical network proliferates, there will be an increased need for a field technician to reconfigure the optical connections within the cabinet. Although spliced optical connections can be reconfigured, it is time consuming for the field technician to identify the appropriate optical fibers of the feeder cable and the distribution cable. Furthermore, it generally requires the expertise of a highly trained field technician to reconfigure the spliced optical connections in a conventional cabinet at an access point in the field. As a result, it is costly for a service provider to frequently dispatch a highly skilled field technician to reconfigure the optical connections within a conventional cabinet. Once again, the additional expense incurred by the service provider to reconfigure the spliced optical connections ultimately will be passed on to the subscriber in the form of higher cost communications service.
Accordingly, there is a need for an LCC that resolves the aforementioned difficulties associated with the inevitable proliferation of an all-optical telecommunications network. There is a further need for the optical connections within the LCC to be well organized and easily accessible to assist a less skilled field technician to identify and reconfigure the optical connections within the cabinet. The present invention solves these, as well as other, problems by providing an LCC for interconnecting at least one optical fiber of a feeder cable with two or more optical fibers of at least one distribution cable at a local convergence point in an optical network. The configuration of the LCC permits the optical connections to be organized in a space efficient manner that increases the fiber capacity of the cabinet and allows a field technician of ordinary skill to reconfigure the optical connections within the cabinet in a timely manner.